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    <script>
        /* Number.isFinite判读是否是有限数 */
        console.log(Number.isFinite(5.1));
        console.log(Number.isFinite(NaN));
        console.log(Number.isFinite(100/0));
        console.log(Number.isFinite(Infinity));

        // Number.isNaN 判断是否是NaN
        console.log(Number.isNaN(NaN));
        console.log(Number.isNaN(461532));

        // Number.isInteger判读一个数是否是个整数
        console.log(Number.isInteger(5.2));

        // 去除小数据
        console.log(Math.trunc(5.6));
        // Math.sign 判断一个数据是正数（1） 负数（-1） 0还是0
        console.log(Math.sign(-2));
        // 把Math上常见的方法总结一下
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